A series of laboratory experiments will be conducted to investigate the feasibility of using an acoustic-based detection technique as a real time, in-situ indicator for laser-induced kidney/gallstone fragmentation. The aim will be to establish a reliable correlation between the achievement of stone demise due to laser-driven fragmentation and the resulting acoustic signature generated. If successful, such a diagnostic technique would provide an extremely valuable non-visual and instaneous monitor during the clinical procedure. In addition to indicating when stone fragmentation is complete, the acoustic monitor could aid in pinpointing the laser probe and guiding the selection of laser power level. The methodology for achieving these goals will involve, for the Phase I grant, performing well-controlled and well-diagnosed laboratory experiments on a variety of kidney and gallstone samples irradiated by a repetitively pulsed tuneable dye laser. Stone response will be characterized using in-situ diagnostics such as hydrophones, an impulse detector, and high speed photography as well as post-test analyses for stone mass loss and fragment size distribution. The principal aim of the experiments will be to establish a reliable correlation between the character and degree of stone fragmentation and the resulting acoustic signature observed.